Bootstrap 4 table generator with NULL values in result-set

Wappler Version : 2.1.5
Operating System : Mac Editor / PHP 7.2 deploy

Expected behavior

When using the Bootstrap 4 Table generator using sortable columns, NULL values in the database should remain NULL in the display, and should be treated as an empty string when sorting.

Actual behavior

Values that are NULL are displayed properly on initial load, however erroneous values are displayed from other records in the query.

How to reproduce

Use this sandbox page:
https://wappler.uniqueideas.com/query_sort.php

Take note of the values shown on initial load (several have no color). Sort the columns, and notice that all values have a color.

This also happens and paged query actions.